The present application relates to an apparatus for sonic coupling between an intake tract or engine compartment and a vehicle interior of a motor vehicle. The apparatus may be positioned within the flow path of uncompressed or compressed intake air. Such apparatus are already known for sound modulation.
For example, DE 199 22 216 describes sound modulation using resonance effects, wherein a cross-section expansion is present within a sound wave path length between the intake tract of an internal combustion engine of a motor vehicle and an interior of the motor vehicle. The expansion leads to the formation of a resonator, so that sound energy from the intake tract is absorbed by resonance within a desired frequency band and can be conducted by the resonator to the vehicle interior, via a membrane functioning as a vibrator.
DE 100 42 012 B4 describes a similar apparatus for creating noise in a motor vehicle. In this known apparatus, there is a hollow body that is divided into at least two spaces by at least one vibratable membrane. The membrane fulfills specific functions, namely preventing a flow in the hollow body, controlling a frequency range, and amplifying noises to be transmitted.
EP 1 138 887 A2 describes an acoustic transducer for exhaust pulsation. The transducer is designed in the form of an impedance transducer that radiates engine-related sound by coupling to the pulsations of an exhaust flow using a membrane in the interior of a motor vehicle. In this case, as well, resonance characteristics are used for adjusting the radiated airborne sound.
EP 1 365 120 B1 discloses an acoustic transducer in which the radiated sound is adjustable, largely independent of changes in pressure at the input of a transmission body. A rigid or stiff vibration body is used that is vibratably held using a mount. The mount can be displaced against elastic force in the vibration direction of the vibration body. Low-frequency fluctuations in pressure can thus be compensated in the input area of the transmission body using corresponding relative displacements of the mount, together with the vibration body held thereon, in that the mount displaces until the elastic force creates an equilibrium. In contrast to this, high frequency airborne sound that is to be coupled out can excite the vibration body to vibrate in order to cause radiation of audible modulated airborne sound.
EP 1 306 829 A2 discloses an apparatus for transmitting internal combustion engine sounds that comprises a housing in which a separating wall is located. A flap element passes through the separating wall.
DE 101 49 169 C1 relates to an acoustic transducer head. The transducer is designed so that exhaust pulsations of an internal combustion engine of a motor vehicle are converted to vibrations in a largely closed space. In addition, there is functionality even at static pressures of 0.5 to 1 bar, because an excitation membrane is coupled either to a sound radiation membrane or to a body sound exciter with pressure compensation. The necessity for either two membranes, or for one membrane and a body sound exciter, demonstrates the complexity of this structure.
Another apparatus for creating noise in a motor vehicle is disclosed in DE 102 23 873 A1, which describes a sound transmission device that has at least two vibratable elements. An acoustically inactive wall is arranged between the elements, which are coupled via a connector that passes through the wall. This structure is very complicated due to the number of parts.
Although the above acoustic transducers are known in the art, there is still a need for a cost-effective device with a long service life, which can be used for the intentional radiation of sound into the interior of a motor vehicle.